Estimation question
How many reviews are left on Amazon on a given Monday?
- Amazon
- Estimation
- Medium
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What this question tests
Funnel-based estimation: converting total order volume into a review count using a realistic review-leave rate.
How to approach it
- Estimate Amazon's daily US order volume from a rough annual figure divided across the year, adjusted slightly for a weekday like Monday.
- Estimate what fraction of orders result in a delivered item eligible for review by Monday, accounting for shipping lag, so use orders delivered, not placed, that day.
- Apply a realistic review-leave rate, commonly cited around 1-5% of purchases, higher for some categories.
- Multiply delivered-eligible orders by the review rate to get total reviews left that day.
- Sanity check the order of magnitude against the known scale of reviews visible across Amazon's catalog.
What a strong answer includes
- Distinguishes orders placed from orders delivered, since reviews follow delivery with a lag.
- States a specific, labeled review-leave-rate assumption instead of an arbitrary final number.
- Arrives at a plausible order of magnitude, low hundreds of thousands per day, and sanity-checks it.
Common mistakes
- Using purchase volume directly without accounting for shipping lag before a review can be left.
- Not stating the review-leave-rate assumption, the single biggest driver of the final number.
Likely follow-up questions
- How would incentivized reviews or Vine reviewers change this estimate?
- How would the review rate differ between categories like electronics and groceries?
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Learn the skill behind it
Chapters of the AI PM course that teach what this question tests.
- Chapter 2: Data fluency: SQL, logs, and reading the truth yourself
- Chapter 9: Prove it paid off: outcomes, economics, and pricing
- Chapter 14: Get the job: the AI PM interview loop